Their greatest value to themselves can be decided by themselves. But if they want to date other people then their value can be calculated the same way a market of buyers and sellers of items calculate value. Its no secret men prefer younger and prettier girls. Its no secret women like accomplished men.
People are free to have whatever preferences they wish, but preferences are diverse (rather than being monolithic as you imply), and aggregate preferences are largely irrelevant - if my partner values my ability to do handstands, I need not concern myself with the popularity of handstands.
Handstands wont win you any marriage material partners, though maybe it can win you 1 or 2 numbers in a mall in Vegas. Preferences are diverse, but the same biological needs drive humanity since hundreds of thousands of years ago. Beauty and ambition have both evolved as a result of procreation.
